1 //#define DEBUG 2 #include <linux/spinlock.h> 3 #include <linux/blkdev.h> 4 #include <linux/hdreg.h> 5 #include <linux/virtio.h> 6 #include <linux/virtio_blk.h> 7 #include <linux/scatterlist.h> 8 9 #define PART_BITS 4 10 11 static int major, index; 12 13 struct virtio_blk 14 { 15 spinlock_t lock; 16 17 struct virtio_device *vdev; 18 struct virtqueue *vq; 19 20 /* The disk structure for the kernel. */ 21 struct gendisk *disk; 22 23 /* Request tracking. */ 24 struct list_head reqs; 25 26 mempool_t *pool; 27 28 /* What host tells us, plus 2 for header & tailer. */ 29 unsigned int sg_elems; 30 31 /* Scatterlist: can be too big for stack. */ 32 struct scatterlist sg[/*sg_elems*/]; 33 }; 34 35 struct virtblk_req 36 { 37 struct list_head list; 38 struct request *req; 39 struct virtio_blk_outhdr out_hdr; 40 struct virtio_scsi_inhdr in_hdr; 41 u8 status; 42 }; 43 44 static void blk_done(struct virtqueue *vq) 45 { 46 struct virtio_blk *vblk = vq->vdev->priv; 47 struct virtblk_req *vbr; 48 unsigned int len; 49 unsigned long flags; 50 51 spin_lock_irqsave(&vblk->lock, flags); 52 while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) { 53 int error; 54 55 switch (vbr->status) { 56 case VIRTIO_BLK_S_OK: 57 error = 0; 58 break; 59 case VIRTIO_BLK_S_UNSUPP: 60 error = -ENOTTY; 61 break; 62 default: 63 error = -EIO; 64 break; 65 } 66 67 if (blk_pc_request(vbr->req)) { 68 vbr->req->resid_len = vbr->in_hdr.residual; 69 vbr->req->sense_len = vbr->in_hdr.sense_len; 70 vbr->req->errors = vbr->in_hdr.errors; 71 } 72 73 __blk_end_request_all(vbr->req, error); 74 list_del(&vbr->list); 75 mempool_free(vbr, vblk->pool); 76 } 77 /* In case queue is stopped waiting for more buffers. */ 78 blk_start_queue(vblk->disk->queue); 79 spin_unlock_irqrestore(&vblk->lock, flags); 80 } 81 82 static bool do_req(struct request_queue *q, struct virtio_blk *vblk, 83 struct request *req) 84 { 85 unsigned long num, out = 0, in = 0; 86 struct virtblk_req *vbr; 87 88 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); 89 if (!vbr) 90 /* When another request finishes we'll try again. */ 91 return false; 92 93 vbr->req = req; 94 switch (req->cmd_type) { 95 case REQ_TYPE_FS: 96 vbr->out_hdr.type = 0; 97 vbr->out_hdr.sector = blk_rq_pos(vbr->req); 98 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 99 break; 100 case REQ_TYPE_BLOCK_PC: 101 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; 102 vbr->out_hdr.sector = 0; 103 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 104 break; 105 case REQ_TYPE_LINUX_BLOCK: 106 if (req->cmd[0] == REQ_LB_OP_FLUSH) { 107 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH; 108 vbr->out_hdr.sector = 0; 109 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 110 break; 111 } 112 /*FALLTHRU*/ 113 default: 114 /* We don't put anything else in the queue. */ 115 BUG(); 116 } 117 118 if (blk_barrier_rq(vbr->req)) 119 vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; 120 121 sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr)); 122 123 /* 124 * If this is a packet command we need a couple of additional headers. 125 * Behind the normal outhdr we put a segment with the scsi command 126 * block, and before the normal inhdr we put the sense data and the 127 * inhdr with additional status information before the normal inhdr. 128 */ 129 if (blk_pc_request(vbr->req)) 130 sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len); 131 132 num = blk_rq_map_sg(q, vbr->req, vblk->sg + out); 133 134 if (blk_pc_request(vbr->req)) { 135 sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, 96); 136 sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr, 137 sizeof(vbr->in_hdr)); 138 } 139 140 sg_set_buf(&vblk->sg[num + out + in++], &vbr->status, 141 sizeof(vbr->status)); 142 143 if (num) { 144 if (rq_data_dir(vbr->req) == WRITE) { 145 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; 146 out += num; 147 } else { 148 vbr->out_hdr.type |= VIRTIO_BLK_T_IN; 149 in += num; 150 } 151 } 152 153 if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) { 154 mempool_free(vbr, vblk->pool); 155 return false; 156 } 157 158 list_add_tail(&vbr->list, &vblk->reqs); 159 return true; 160 } 161 162 static void do_virtblk_request(struct request_queue *q) 163 { 164 struct virtio_blk *vblk = q->queuedata; 165 struct request *req; 166 unsigned int issued = 0; 167 168 while ((req = blk_peek_request(q)) != NULL) { 169 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems); 170 171 /* If this request fails, stop queue and wait for something to 172 finish to restart it. */ 173 if (!do_req(q, vblk, req)) { 174 blk_stop_queue(q); 175 break; 176 } 177 blk_start_request(req); 178 issued++; 179 } 180 181 if (issued) 182 vblk->vq->vq_ops->kick(vblk->vq); 183 } 184 185 static void virtblk_prepare_flush(struct request_queue *q, struct request *req) 186 { 187 req->cmd_type = REQ_TYPE_LINUX_BLOCK; 188 req->cmd[0] = REQ_LB_OP_FLUSH; 189 } 190 191 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, 192 unsigned cmd, unsigned long data) 193 { 194 struct gendisk *disk = bdev->bd_disk; 195 struct virtio_blk *vblk = disk->private_data; 196 197 /* 198 * Only allow the generic SCSI ioctls if the host can support it. 199 */ 200 if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI)) 201 return -ENOTTY; 202 203 return scsi_cmd_ioctl(disk->queue, disk, mode, cmd, 204 (void __user *)data); 205 } 206 207 /* We provide getgeo only to please some old bootloader/partitioning tools */ 208 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 209 { 210 struct virtio_blk *vblk = bd->bd_disk->private_data; 211 struct virtio_blk_geometry vgeo; 212 int err; 213 214 /* see if the host passed in geometry config */ 215 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY, 216 offsetof(struct virtio_blk_config, geometry), 217 &vgeo); 218 219 if (!err) { 220 geo->heads = vgeo.heads; 221 geo->sectors = vgeo.sectors; 222 geo->cylinders = vgeo.cylinders; 223 } else { 224 /* some standard values, similar to sd */ 225 geo->heads = 1 << 6; 226 geo->sectors = 1 << 5; 227 geo->cylinders = get_capacity(bd->bd_disk) >> 11; 228 } 229 return 0; 230 } 231 232 static const struct block_device_operations virtblk_fops = { 233 .locked_ioctl = virtblk_ioctl, 234 .owner = THIS_MODULE, 235 .getgeo = virtblk_getgeo, 236 }; 237 238 static int index_to_minor(int index) 239 { 240 return index << PART_BITS; 241 } 242 243 static int __devinit virtblk_probe(struct virtio_device *vdev) 244 { 245 struct virtio_blk *vblk; 246 int err; 247 u64 cap; 248 u32 v; 249 u32 blk_size, sg_elems; 250 251 if (index_to_minor(index) >= 1 << MINORBITS) 252 return -ENOSPC; 253 254 /* We need to know how many segments before we allocate. */ 255 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, 256 offsetof(struct virtio_blk_config, seg_max), 257 &sg_elems); 258 if (err) 259 sg_elems = 1; 260 261 /* We need an extra sg elements at head and tail. */ 262 sg_elems += 2; 263 vdev->priv = vblk = kmalloc(sizeof(*vblk) + 264 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL); 265 if (!vblk) { 266 err = -ENOMEM; 267 goto out; 268 } 269 270 INIT_LIST_HEAD(&vblk->reqs); 271 spin_lock_init(&vblk->lock); 272 vblk->vdev = vdev; 273 vblk->sg_elems = sg_elems; 274 sg_init_table(vblk->sg, vblk->sg_elems); 275 276 /* We expect one virtqueue, for output. */ 277 vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests"); 278 if (IS_ERR(vblk->vq)) { 279 err = PTR_ERR(vblk->vq); 280 goto out_free_vblk; 281 } 282 283 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); 284 if (!vblk->pool) { 285 err = -ENOMEM; 286 goto out_free_vq; 287 } 288 289 /* FIXME: How many partitions? How long is a piece of string? */ 290 vblk->disk = alloc_disk(1 << PART_BITS); 291 if (!vblk->disk) { 292 err = -ENOMEM; 293 goto out_mempool; 294 } 295 296 vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); 297 if (!vblk->disk->queue) { 298 err = -ENOMEM; 299 goto out_put_disk; 300 } 301 302 vblk->disk->queue->queuedata = vblk; 303 304 if (index < 26) { 305 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); 306 } else if (index < (26 + 1) * 26) { 307 sprintf(vblk->disk->disk_name, "vd%c%c", 308 'a' + index / 26 - 1, 'a' + index % 26); 309 } else { 310 const unsigned int m1 = (index / 26 - 1) / 26 - 1; 311 const unsigned int m2 = (index / 26 - 1) % 26; 312 const unsigned int m3 = index % 26; 313 sprintf(vblk->disk->disk_name, "vd%c%c%c", 314 'a' + m1, 'a' + m2, 'a' + m3); 315 } 316 317 vblk->disk->major = major; 318 vblk->disk->first_minor = index_to_minor(index); 319 vblk->disk->private_data = vblk; 320 vblk->disk->fops = &virtblk_fops; 321 vblk->disk->driverfs_dev = &vdev->dev; 322 index++; 323 324 /* If barriers are supported, tell block layer that queue is ordered */ 325 if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) 326 blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_DRAIN_FLUSH, 327 virtblk_prepare_flush); 328 else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) 329 blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); 330 331 /* If disk is read-only in the host, the guest should obey */ 332 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 333 set_disk_ro(vblk->disk, 1); 334 335 /* Host must always specify the capacity. */ 336 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 337 &cap, sizeof(cap)); 338 339 /* If capacity is too big, truncate with warning. */ 340 if ((sector_t)cap != cap) { 341 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 342 (unsigned long long)cap); 343 cap = (sector_t)-1; 344 } 345 set_capacity(vblk->disk, cap); 346 347 /* We can handle whatever the host told us to handle. */ 348 blk_queue_max_phys_segments(vblk->disk->queue, vblk->sg_elems-2); 349 blk_queue_max_hw_segments(vblk->disk->queue, vblk->sg_elems-2); 350 351 /* No need to bounce any requests */ 352 blk_queue_bounce_limit(vblk->disk->queue, BLK_BOUNCE_ANY); 353 354 /* No real sector limit. */ 355 blk_queue_max_sectors(vblk->disk->queue, -1U); 356 357 /* Host can optionally specify maximum segment size and number of 358 * segments. */ 359 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, 360 offsetof(struct virtio_blk_config, size_max), 361 &v); 362 if (!err) 363 blk_queue_max_segment_size(vblk->disk->queue, v); 364 else 365 blk_queue_max_segment_size(vblk->disk->queue, -1U); 366 367 /* Host can optionally specify the block size of the device */ 368 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, 369 offsetof(struct virtio_blk_config, blk_size), 370 &blk_size); 371 if (!err) 372 blk_queue_logical_block_size(vblk->disk->queue, blk_size); 373 374 add_disk(vblk->disk); 375 return 0; 376 377 out_put_disk: 378 put_disk(vblk->disk); 379 out_mempool: 380 mempool_destroy(vblk->pool); 381 out_free_vq: 382 vdev->config->del_vqs(vdev); 383 out_free_vblk: 384 kfree(vblk); 385 out: 386 return err; 387 } 388 389 static void __devexit virtblk_remove(struct virtio_device *vdev) 390 { 391 struct virtio_blk *vblk = vdev->priv; 392 393 /* Nothing should be pending. */ 394 BUG_ON(!list_empty(&vblk->reqs)); 395 396 /* Stop all the virtqueues. */ 397 vdev->config->reset(vdev); 398 399 del_gendisk(vblk->disk); 400 blk_cleanup_queue(vblk->disk->queue); 401 put_disk(vblk->disk); 402 mempool_destroy(vblk->pool); 403 vdev->config->del_vqs(vdev); 404 kfree(vblk); 405 } 406 407 static struct virtio_device_id id_table[] = { 408 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 409 { 0 }, 410 }; 411 412 static unsigned int features[] = { 413 VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, 414 VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, 415 VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_FLUSH 416 }; 417 418 /* 419 * virtio_blk causes spurious section mismatch warning by 420 * simultaneously referring to a __devinit and a __devexit function. 421 * Use __refdata to avoid this warning. 422 */ 423 static struct virtio_driver __refdata virtio_blk = { 424 .feature_table = features, 425 .feature_table_size = ARRAY_SIZE(features), 426 .driver.name = KBUILD_MODNAME, 427 .driver.owner = THIS_MODULE, 428 .id_table = id_table, 429 .probe = virtblk_probe, 430 .remove = __devexit_p(virtblk_remove), 431 }; 432 433 static int __init init(void) 434 { 435 major = register_blkdev(0, "virtblk"); 436 if (major < 0) 437 return major; 438 return register_virtio_driver(&virtio_blk); 439 } 440 441 static void __exit fini(void) 442 { 443 unregister_blkdev(major, "virtblk"); 444 unregister_virtio_driver(&virtio_blk); 445 } 446 module_init(init); 447 module_exit(fini); 448 449 MODULE_DEVICE_TABLE(virtio, id_table); 450 MODULE_DESCRIPTION("Virtio block driver"); 451 MODULE_LICENSE("GPL"); 452